This is a Phase II study designed to estimate the efficacy of weekly low-dose PEG-Intron in pediatric patients with CNS tumors, beginning 2-10 weeks after completion of radiation therapy. The endpoint of the trial is 2-year survival compared to historical controls who have received radiation alone. Patients undergo extensive imaging analysis. Accrual to this trial has been completed, patients are being followed for endpoint analyses, and biologic samples are being evaluated. All patients have tolerated the PEG-Intron therapy well, with no adverse events directly attributable to the study agent. Overall study results, including 2 year survival, have been published in the journal, Cancer. We showed that patients receiving PEG-Intron have a median time to progression of 7 months compared to similar patients on recently completed consortia trials, who have a median time to progression of 4-5 months. Accrual to this trial and the primary endpoint are complete. We are now evaluating batched patient samples for a number of biomarkers, which will be correlated to outcome.